Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-07-05
2001-11-13
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S126200
Reexamination Certificate
active
06316157
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
Related Background Art
The present invention relates to non-metallic black toner used for electrophotography and an image forming method using the toner.
A developer using an electrophotographic process has been manufactured so far in accordance with the so-called pulverization method of adding a coloring agent, a charge control agent, and moreover a wax component to a binder resin such as a polyester resin, styrene-acrylic resin, or epoxy resin and melting, kneading, and uniformly dispersing them, thereafter pulverizing them into a predetermined particle size, and moreover removing excessive fine powder and coarse powder from them by a classifier.
Moreover, toner-particle manufacturing methods in accordance with the suspension polymerization method are disclosed in Japanese Patent Publication Nos. 36-10231, 43-10799, and 51-14895. The suspension polymerization method is a method of obtaining toner particles having a desired particle diameter by uniformly dissolving or dispersing polymerizable monomer, coloring agent, and polymerization initiator, and moreover cross-linking agent, charge control agent, and other additives according to necessity and thereby preparing a monomer composition and thereafter, dispersing the monomer composition in a continuous phase containing a dispersion stabilizer such as an aqueous phase by a proper agitator and polymerizing it.
This method does not include the pulverizing step and therefore, it is unnecessary to give brittleness to toner particles and moreover, this method uses a large quantity of low-softening-point material that has hardly been used by a conventional crushing method. Therefore, the material selection width is increased. Moreover, a wax component or coloring agent that is a hydrophobic material is not easily exposed to the surface of a toner particle. Therefore, this method has a feature that a toner carrying member, a photosensitive member, a transfer roller, and a fixing unit are not easily contaminated and it is recently noticed.
Moreover, digital full-color copying machines and full-color printers have been practically used so far and thereby, it has been necessary to further improve such characteristics as the image fidelity and color reproducibility of a toners. In the case of a digital full-color copying machine and a full-color printer, a plurality of toners are superposed and an image is formed. Therefore, requests for the toner fixing property and color reproducibility are increasingly raised. Polyester resin is preferably used as a binder resin for toner for meeting these requests.
However, polyester resin is easily influenced by moisture at a high humidity because it has a hydroxyl value and toner containing polyester resin easily causes a charged quantity to decrease at a high humidity.
Moreover, in manufacturing toner in accordance with the pulverization method and polymerization method, many problems occur when using carbon black as a coloring agent.
First, carbon black has a small primary particle diameter and a large specific surface area compared to other pigments. Therefore, carbon black is hardly dispersed or maldistributed on the surface of a toner particle and easily produces free carbon black. Because carbon black is fine powder having a high stickiness, presence of free carbon black causes the flowabllity of toner to deteriorate and prevents preferable frictional electrification, and particularly deteriorates the reproducibility of a half-tone image. Moreover, when carbon black is not completely dispersed, a problem also occurs that a sufficient image density is not obtained.
Secondly, electric charges of carbon black easily leak when the carbon black is present on the surface of toner because the carbon black has conductivity. Therefore, when forming an image by using the toner, fog, toner scatter, or transfer skip occurs.
Moreover, when manufacturing toner in accordance with the polymerization method, carbon black has a functional group for preventing polymerization of a polymerizable monomer such as a quinone group on its surface. Therefore, the polymerization rate lowers, the polymerization degree does not rise, particles become unstable when they are formed, cohesion or coalescence is caused, and it is difficult to take out the carbon black as particles.
To solve the above problems, Japanese Patent Application Laid-Open No. 56-116044 discloses a method of using carbon black whose surface is grafted and Japanese Patent Application Laid-Open No. 63-210849 discloses a method of using carbon black whose surface is treated by an aluminum coupling agent. However, it is industrially difficult to use these methods because the step of treating the surface of carbon black is complex and takes a lot of time, and requires a lot of manufacturing cost.
Though Japanese Patent Application Laid-Open Nos. 64-35457 and 1-145664 are applications relating to improvement of dispersibility of carbon black, it cannot be said yet that the dispersibility is not completely solved.
Moreover, Japanese Patent Application Laid-Open Nos. 7-64337 and 10-186713 disclose the improvement of dispersibility of carbon black and electrification property of toner by combining carbon black having a specific solid-state property with an azo-based iron compound having a specific structure. For example, the method disclosed in Japanese Patent Application Laid-Open No. 10-186713 is a superior method for obtaining toner having a high tinting strength and a stable electrification property but it has a slight problem on solid image uniformity and durability under a high-humidity environment.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a non-metallic black toner solving the above problems and an image forming method using the toner.
It is another object of the present invention to provide a non-metallic black toner having a high tinting strength and an image forming method using the toner.
It is still another object of the present invention to provide non-metallic black toner in which quick electrification is performed in any environment and which has a preferable electrified quantity and an image forming method using the toner.
It is still another object of the present invention to provide non-metallic black toner having a small weight-average particle diameter and a sharp particle size distribution and an image forming method using the toner.
It is still another object of the present invention to provide non-metallic black toner having the above superior characteristics independently of the pulverization method or polymerization method and an image forming method using the toner.
An object of the present invention is to provide a non-metallic black toner comprising toner particles containing at least a binder resin, a carbon black and an organometallic compound, and an external additive, wherein:
the toner particles contain 10 to 200 ppm of at least one kind of alkali metal element;
the toner particles contain at least one kind of organometallic compound selected from organoiron compounds, organoaluminum compounds, organochromium compounds, organozinc compounds, organoboron compounds, and organozirconium compounds;
the toner particles contain a polyester resin as a resin component; and
the non-metallic black toner has a weight-average particle diameter of 4 to 11 &mgr;m,
the following loss tangents tan &dgr; shown by dielectric loss factor ∈″/dielectric constant ∈′ at frequencies of 5×10
4
Hz and 10
5
Hz:
tan &dgr; (5×10
4
Hz)≦0.0125
tan &dgr; (10
5
Hz)≦0.0105,
a Carr's flowability index of 50 or more, and
a Carr's floodability index of 65 or more.
Another object of the present invention is to provide an image forming method comprising:
a development stop of developing an electrostatic latent image held by a latent image holding member with a non-metallic black toner to form a toner image;
a transfer step of transferring the toner image formed on the latent image holding member onto a recording material throug
Katsuta Yasushi
Mikuriya Yushi
Nakayama Ken-ichi
Okado Kenji
Taya Masaaki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Goodrow John
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